My concept for this: "Dark Fantasyland" would have three rides, two restaurants, and three shops. I tried to stay away from characters like Gaston, the Evil Queen, Ursula, and Maleficent that are already featured elsewhere.
I also wanted to use a concept that I saw online where the entrance would be an elevated walkway between Village Haus and Tales with Belle (replaceing the restrooms), so it ties back into Fantasyland, with a spur going off towards the Haunted Mansion queue. In order to pull that off, I'm picturing the need for a lot of buildings to cover up the back of show buildings, so it would feature more facades and buildings.
You'd enter an alleyway past Village Haus, next to "Stromboli Swings," a Wave Swinger-style ride themed to Pinocchio's showman. The queue line would have posters for Pleasure Island and other traveling shows. The operator booth would look like the caravan from the animated movie, while different pipe organ/calliope songs would play during the ride, including "There Are No Strings On Me." Riders would look like they're "on strings" in the seats, while the ride itself keeps the Italian stylings of the film and character. Next to that would be a Monstro shop, where you enter through his mouth and would look very similar to the shop at Tokyo DisneySea in Mermaid Lagoon.
Second ride (show building behind Be Our Guest) would be "The Curse of Jafar," a traditional omnimover dark ride that explores the dark magic of the Aladdin character, including his transformation into being trapped as a Genie. Guests would ride in lamps of varying shapes/colors, and Jafar would narrate his journey through on-board 3D audio, which give it a creepy, disembodied voice effect. There would also be an emphasis on optical illusions in this ride, including scenes where the floor looks much deeper than it really is. (Also, if nothing else, this gives an excuse to remove the Magic Carpets in Adventureland and keep this as the sole Aladdin ride in the park).
Dr Facilier would get a "Voodoo Emporium" shop, which would be mostly candy/snacks. The Queen of Hearts from Alice in Wonderland would get her own garden walk-through, although this is more intended as photo ops and not an entire attraction. Cruella's "House of Style" would be the main shop coming up next, featuring her famous car in a wreck outside a building covered in Dalmatian spots. This would sell apparel, and connect to "Club Underworld," a restaurant vaguely themed to Hades from Hercules. This will have a sinister art-deco look, and specializing in mocktails and spicy foods.
The other restraint would be "Prince John's Feast," which would be a new sitdown restaurant themed after the Robin Hood film. I'd also have a few easter eggs as tributes to villains that aren't represented elsewhere, like Frollo from Hunchback, Yzma from Emperor's New Groove, Scar from The Lion King, Lady Tremaine from Cinderella, and The Horned King from Black Caldron.
The big E-Ticket here is "Bald Mountain," a new suspended coaster with on-board audio, multiple launches, and a Chernabog AA. I don't really have much more than that, but making the ride center on Fantasia seems like the last big opportunity for that at the WDW resort, so I'm running with it. This would go over what's currently part of the Rivers of America, which would be shortened a bit. The path would also connect to Haunted Mansion, providing a proper transition there, as well as to the Encanto/Coco area.